1. Field of the Invention
Embodiments of the invention relate to a semiconductor device and a method of manufacturing a semiconductor device.
2. Description of the Related Art
A power semiconductor module is a power semiconductor device having one or more built-in power semiconductor chips, partially or entirely configuring a conversion connection and having a structure electrically insulated between the power semiconductor chip(s) and a stacked substrate or metal substrate. In terms of industrial applications, power semiconductor modules are used in, for example, motor driving control inverters for elevators and the like. In recent years, power semiconductor modules have come to be widely used in motor driving control inverters for automotive use. To improve fuel efficiency, automotive inverters have to be compact and light-weight. Further, since automotive inverters are installed near the drive motor in the engine room, long-term reliability at high operating temperatures is also demanded of these inverters.
A structure of a typical insulated gate bipolar transistor (IGBT) power semiconductor module will be described as an example of a structure of a conventional power semiconductor module.
FIG. 7 is a cross-sectional view of a conventional structure of a power semiconductor module. As depicted in FIG. 7, a power semiconductor module includes a power semiconductor chip 1, an insulating substrate 2, bonding members 3b, 3c, an electrode pattern 4, a metal substrate 5, a terminal case 7, a sealing resin 8, a metal terminal 9, a metal wire 10, and a cover 11.
The power semiconductor chip 1 is a semiconductor element such as an IGBT or a diode chip, etc. Both sides of the insulating substrate 2 have the electrode pattern 4. On the electrode pattern 4 on one side, the power semiconductor chip 1 is bonded by the bonding member 3b of, for example, solder. On the electrode pattern 4 on the other side, the metal substrate 5 having a radiator fin (not depicted) is bonded by the bonding member 3c of, for example, solder. A substrate in which an electrode pattern is provided on at least one surface of the insulating substrate 2 is called a stacked substrate. Further, as wiring for electrical connection, the metal wire 10 is connected to an upper surface of the power semiconductor chip 1 and the electrode pattern 4. The metal terminal 9 for external connection is provided on an upper surface of the electrode pattern 4. Further, to insulate and protect the power semiconductor chip 1, the terminal case 7 is filled with the sealing resin 8, e.g., silicone gel of a low elastic modulus, and a package is completed by the cover 11.
Compared to power semiconductor modules for industrial use, power semiconductor modules for automotive use have to be compact and light-weight due to installation space constraints. Further, since the output power density to drive the motor becomes high, the semiconductor chip temperature during operation becomes high and accordingly, demand for long-term reliability at high operating temperatures is high. Therefore, a power semiconductor module structure providing long-term reliability and high temperature operation is demanded.
Nonetheless, with a conventional metal-wire wiring scheme using metal wire, the gauge of the wire affects current density at the time of energization and to provide the current necessary for operation, the number of wires has to be increased. Therefore, with the metal-wire wiring scheme, the upper surface of the semiconductor chip and the electrode pattern have to be connected by multiple metal wires and the wire bonding area of the power semiconductor module increases whereby the size of the power semiconductor module itself increases.
Thus, to resolve these issues, a switch to a lead frame interconnect scheme from the conventional metal-wire wiring scheme is being studied. A lead frame interconnect scheme involves using a lead frame interconnection formed by a metal plate molding process, supporting and fixing the semiconductor chip, and connecting the semiconductor chip and the electrode pattern.
Further, compared to conventional power semiconductor modules for industrial use, power semiconductor modules for automotive use have a high operating temperature and therefore, with a conventional silicone gel sealed structure, heat resistance becomes a problem and therefore, a sealing resin structure using a thermosetting resin such as an epoxy resin is being studied.
With regard to the lead frame interconnect scheme, for example, one semiconductor device includes a first lead frame, a second lead frame provided apart from the first lead frame, a semiconductor chip provided on the first lead frame, resin sealing the semiconductor chip, and a connector (for example, refer to Japanese Laid-Open Patent Publication No. 2015-142072). Further, another semiconductor device includes a lead frame that is a first interconnection connected to a first main electrode, a wire frame that is a second interconnection connected to a second main electrode, and a lead frame that is a third interconnection connected to a control electrode (for example, refer to Japanese Laid-Open Patent Publication No. 2011-199039). Further, another semiconductor device includes a semiconductor element, a lead frame that is a terminal member in which one end Ei portion is bonded to the semiconductor element and another end Ex is electrically connected to an external device, and a sealing body sealing 1 sealing the one end Ei portion of the terminal member and the semiconductor element (for example, refer to Japanese Laid-Open Patent Publication No. 2012-156450).